林火与水土流失

本文综述了林地用火与水土流失关系, 阐明在北方及南方平原林地"规定用火"或"迹地用火"后, 土壤渗透性能得到改善, 水土流失较为轻微; 而在南方山区, 强度火烧后水土流失较为严重, 陡坡地段可蚀性较强的土壤水土流失尤为严重。根据火后土壤生境特点及用火现状, 指出林业用火与耕作制度有机组合, 形成特定的"农林业系统", 将为南方林业生产带来重大改革。     

Forest Dynamics and Resulting Animal and Plant Population Changes at the Stand and Landscape Levels

Abstract

A disturbance to a stand is often part of larger event which impacts a large landscape area. Across a landscape, a disturbance event leaves a mosaic of” conditions. The event can miss some Stands, kill all trees in other stands, and kill only some trees in other stands. Stands regrow through certain processes and create certain structures after a disturbance; time at which each structure is achieved varies with specific stand and disturbance conditions. Each structure is utilized by certain plant and animal species, but not others. A disturbance leaves many openings across the landscape and allows species which utilize these openings to expand their populations. At the same time, “closed forest” species become extirpated or confined to isolated “refugia” missed by the disturbance. With regrowth the “open” species become confined to small, isolated “refugia” and the closed forest species increase in number. Landscape areas have probably always had various fluctuations in plant and animal populations.     

基于ST2和ADAMS的圆锯机进料夹紧机构动态仿真与优化

进料夹紧机构是双工位截段圆锯机的关键组成部分,在工作过程中由于工作频繁致使其非常容易损坏.采用ST2建立三维模型导入虚拟样机仿真软件ADAMS对进料夹紧机构进行仿真,以确定进料夹紧机构中弹簧的扭矩及变形曲线,并对弹簧进行优化选择,分析其受力状态及使用寿命,为设计合理的进料夹紧机构提供理论依据.     

我国的沙尘暴及防治问题探讨

近几年,沙尘暴造成的危害引起社会各界的广泛关注,如何防治沙尘暴成为人们普遍关心的话题。沙尘暴防治不仅是一个技术问题,而且也是一个认识问题。因此,正确认识沙尘暴的来源、路径、危害现状和产生的原因,对今后制定防治沙尘暴的思路和措施极为重要。本文通过对沙尘暴监测结果的分析,在长期指导防沙治沙实践的基础上,认为沙尘暴不可能彻底根治,但可以通过大规模建设以灌木为主的地表植被,进行预防和治理,再配合农业、牧业、水利及农村能源等综合措施,可以最大限度地减轻沙尘暴造成的危害。     

Apiculture and forestry (bees and trees)

Honey bees are found associated with forests globally. Flowers of forest trees provide subsistence for honey bees and the trees physically provide shelter for a swarm or bee hive. Forest management and beekeeping have each had a long history both in the United States and globally, but have seldom been integrated or studied in a systematic fashion. Purposeful plantings of trees, as in agroforestry systems, could be designed to favor bee forage or hive protection.Tree growing and beekeeping can easily be combined for several reasons. Both are sustainable on land that is hilly or otherwise less desirable for other agricultural purposes. Both require labor intermittently, and can be sustained while the grower/beekeeper is busy with other farming occupations. Bee hives require very little space, while the bees themselves can forage in a radius of 4 to 5 km. Hives may be located within or near a tree plantation, and utilize both the trees and surrounding other flowering plants for forage. Combining forestry and beekeeping provides annual honey bee products (e.g. honey, beeswax) to supplement income from a landowner's long term forest managements. In areas like Kentucky, where more than half of the forest landowners own 4 ha or less of commercially valuable woodland, it is important to produce economic benefit from those lands without harvesting all the trees. Combining bees and trees is one way of accomplishing this goal. This paper addresses several important known bee-tree interactions which need more systematic study.     

湖南省湿地标准与分类以及湿地资源

为了配合“湖南省湿地保护条例”的实施和加强湿地的有效保护,在以往湿地资源调查的基础上,对湖南省境内重要湿地进行补充调查.依据国际和国家湿地分类系统,结合湖南湿地现状,提出将湖南省湿地划分为2大系统5大类别18个类型.分别介绍了湖南不同湿地类型的主要湿地资源。     

林火与病虫害的相互作用

火是森林生态系统演替过程中的一种自然干扰因子, 在促进森林发育、维持生物多样性特别是景观多样性方面起着积极的作用。森林中的多种干扰间有关联性, 火灾、虫害和病原体之间存在着复杂的相互作用。文中综述了火干扰与森林病虫害的相互影响。火灾会引起森林组成和景观的变化, 进而影响森林病虫的生存与发生条件。病虫害通过改变可燃物特性及其分布, 影响火烧频度和强度。这一研究领域的未来发展趋势是更注重火与病虫害之间的量化关系, 研究结果将为开展科学的林火管理提供理论依据, 实现森林经营的可持续。     

中国竹材制浆造纸及高值化加工利用现状及展望

竹材是一种优良的纤维原料,可用于制浆造纸和提取竹原纤维。竹材的纤维形态、化学成分基本介于针叶木和阔叶木之间,漂白竹浆的品质与木浆相当。虽然竹子存在半纤维素和灰分含量较高等不足,但其α-纤维素含量较高,可制取高得率级溶解浆。竹浆是中国造纸工业鼓励发展的浆种,目前产能在200万t/a以上,且今后几年将出现快速增长势头。竹浆厂每年产生大量的纤维类废弃物。以竹浆生产为主线,提供多种高附加值产品,将是未来竹浆企业获得可持续健康发展的盈利模式。生产溶解浆、生活用纸等新型差异化终端产品,并对制浆过程产生的纤维类废弃物进行高附加值综合利用,制备阻燃型保温材料、乙醇和丁醇等生物质燃料,以及纳米纤维素微晶产品,是现在竹浆企业可供选择的发展路径。竹原纤维具有天然抗菌抑菌性、吸湿除臭、抗紫外光、隔音隔热性等功能特性,是生产高档服装、吸附材料和隔热隔音材料的良好纤维原料。竹原纤维的生产目前已实现工业化,但产业规模有待提高,产品标准亟待制定和完善。     

Sustainability and Biodiversity

Abstract

The implementation of the Rio protocol and the preservation of biodiversity at the national and regional levels is an important step in achieving sustainable forestry. This is indeed a challenging task since our knowledge of the ecology and habitat demands for but a few species is severely restricted. Research in the last years shows that forest species have very different qualitative and spatial demands on their environment, which require complex and broad solutions. This poses a great problem for conservation and often forces societies/decision-makers to make decisions based on assumptions rather than on empirical data. With assumptions follow uncertainty, a factor that is necessary to control. We identify and discuss the uncertainties of steps that are considered to be important for preserving biodiversity on a regional level and exemplify this with cases from southern Sweden. We argue that there is no universal solution for the conservation of biodiversity. In strongly fragmented and transformed regions like southern Sweden, a mix of species approaches and ecosystem approaches is necessary for biodiversity conservation. Programs for preserving biodiversity should be flexible, not rigid, allowing for modifications due to a constantly increasing body of knowledge and environmental changes. Prominent gaps in our knowledge include species dispersal ability and propensity, extinction rates and the species dependence on fragmentation and landscape history. It is possible that the question of responsibility species (a species for which a region has an explicit conservational responsibility) may gain in importance, an issue with far-reaching implications for economy and inter-regional compensatory systems.     

计算机及网络的管理与安全防护

近年来,随着科技的发展,计算机和网络得到飞速发展和应用,已成为社会运转的核心和未来发展的趋势,信息化在为发展带来机遇和便利的同时,也带来安全问题。文章以计算机管理为研究重点,对计算机的管理与安全防护现状进行了分析,并以风险管理理念为指导,从培育风险意识、加强制度建设、运用技术手段、强化监督检查等方面,提出了加强计算机管理的对策。     

防霉抗菌软木地板的制备与性能研究

为了制备具有防霉抗菌功能的环保型软木地板，在水性涂料面漆中加入纳米银抗菌剂和二氧化钛载银抗菌剂，分析抗菌剂类型和添加量对地板性能的影响。结果表明：抗菌剂的加入对软木地板的物理性能无明显影响，但可以有效提高其抗菌性能，且对金黄色葡萄球菌的抑制效果显著优于大肠杆菌；软木本身具有一定的防霉作用，纳米银抗菌剂和二氧化钛载银抗菌剂防霉作用较弱，可通过加入少量防霉剂提高软木地板防霉性。     

Market and technical challenges and opportunities in the area of innovative new materials and composites based on nanocellulosics

This communication is a review over the major market and technical challenges and opportunities for nanocellulosic materials on a large scale but in low-to-medium-end markets. Basically, the potential use of nanocellulose as a wet-end strength additive in papermaking has been known for decades, but not come into operation because of the high-energy costs of producing these materials. Cost performance compared to starch derivatives is one challenge, and the other is to design suitable dewatering/retention aid systems. Other paper applications are as a surface-sizing agent and as a barrier coating material. Major challenges are associated with the high viscosity of nanocellulosic materials and how to apply the nanocellulose in order to obtain good surface coverage. There are several opportunities in the nanocomposite markets. The packaging sector together with the automotive sector and the building sector constitute large potential markets. Challenges are related to the mixing of hydrophobic and hydrophilic materials so that a good dispersion of nanocellulose is obtained. Scaling up of nanocellulose production processes and procedures for nanocomposite manufacturing in order to obtain price–performance in the various applications remains, as expected, the largest challenge     

全国森林资源清查和规划设计调查结果的比较及其使用

介绍了历次一类调查结果和江西省同期一、二类调查主要指标.提出当二类调查全部用抽样控制时,用估计区间作比较,而二类调查部分和全部未作抽样控制时,以允许误差为标准作比较;一类调查资料用于制定本地区的林业计划、规划以及对外数据公布等,二类调查资料用于分解计划、规划到二类调查单位等.     

干旱胁迫对杨树气体交换与荧光参数的影响

以白杨派和黑杨派杨树的盆栽苗为试材,分析了不同干旱胁迫程度对5个杨树的气体交换参数与荧光参数(Fv/Fm、Fmv/Fms)的影响,并对不同树种的耐旱性进行了综合评价。结果表明:①5种杨树净光合速率与蒸腾速率均随苗木叶水势的下降而呈明显下降趋势;在水分胁迫初期,欧洲黑杨和银白杨的净光合速率呈现明显的上升趋势。②在中度干旱胁迫前,5个供试杨树的水分利用效率大部分随叶水势的下降有增大现象。③不同树种的Fv/Fm随叶水势降低总体上呈逐渐下降趋势。④与Fv/Fm相比,Fmv/Fms能更直接地反映光合机构的实际光能捕获能力。⑤当苗木叶水势为-1.5 MPa时,5个树种耐旱性的综合评价结果为:转Bt基因欧洲黑杨>欧洲黑杨>银白杨>银灰杨为欧洲山杨,综合指数评价结果与采用单一指标中的水分利用效率完全一致,与净光合速率相近;水分利用效率证明是一种较为可靠的树种耐旱性评价指标。     

文冠果的特性及其开发应用

文冠果是我国特有的一种集观赏、绿化、油料、药用于一身的优良树种,也是优良园林绿化树种,具有很大的开发利用价值。文中阐述文冠果的植物属性与其生物学特性,分析文冠果在城市绿化中的园林应用方式及开发利用的前景。       

色木槭、拧劲槭生长分析及生长阶段划分初探

以色木槭、拧劲槭天然林解析木为对象,用Logistic模型对树高、胸径、材积生长进行拟合,研究其生长规律。结果表明：树高、材积生长拟合效果良好。色木槭树高生长9 a前为生长前期,9～31 a为速生期,20 a为生长高峰年,31 a后为生长后期;材积生长25 a前为生长前期,25～38 a为速生期,32 a为生长高峰年,38 a后为生长后期。拧劲槭树高生长9 a前为生长前期,9～40 a为速生期,12 a为生长高峰年,40 a后为生长后期;材积生长28 a前为生长前期,28～43 a为速生期,36 a为生长高峰年,43 a后为生长后期。色木槭、拧劲槭树高、胸径生长在15 a前比较接近,15 a后色木槭明显高于拧劲槭;色木槭、拧劲槭材积生长在18 a前比较接近,18 a后色木槭明显高于拧劲槭。     

英山县茶叶产品的发展与品牌创建

本文基于GIS的空间分析,对英山县茶产品的地域分布、产量的提升以及名优茶产品的产量进行了详细的对比分析,揭示了英山县的特色茶叶品牌对经济发展和农户增收的积极作用.进而对英山县茶叶品牌创建的举措进行了深入的探索.     

A comparison of annual transpiration and productivity in monoculture and mixed-species Douglas-fir and red alder stands

Although much is known about drivers of productivity in Douglas-fir and red alder stands, less is known about how productivity may relate to stand transpiration and water use efficiency. We took advantage of a 15-year-old experiment involving Douglas-fir (Pseudotsuga menziesii) and red alder (Alnus rubra) in the western Cascade Range of western Oregon to test the following hypotheses: (a) more productive stands transpire more water, (b) the relationship between productivity and transpiration differs between species, and (c) the relationship between productivity and transpiration differs between sites varying in soil moisture and fertility. Furthermore, the experimental design included alder, a facultative nitrogen-fixing species, which could also affect fertility. Fixed area plots (20 × 20 m) were planted as monocultures of each species or in mixtures at a common density (1100 trees ha⁻¹) in a randomized-block design. Transpiration of Douglas-fir and red alder was measured using heat dissipation sensors installed in eight trees per plot and scaled to the plot level based on sapwood basal area for each species. Although up to 53% of the variability in tree transpiration was explained by basal area, irrespective of species or site conditions, the two stands with the highest biomass and sapwood basal area did not transpire the most. Instead of more productive stands transpiring more water, the greatest variability in both productivity and transpiration was determined by site conditions and to a lesser degree, species composition. For example, 70% of the variation in tree biomass increment (TBI) was determined by leaf area index, which was much higher at the site with higher fertility and soil moisture (p < 0.05). Despite marked phenological and physiological differences, Douglas-fir and red alder performed similarly. Only 19% of annual water use of Douglas-fir occurred between October and March when alder was leafless. Also, there was no evidence of a fertilization effect of the nitrogen-fixing red alder on the Douglas-fir: the nitrogen concentration and N-isotopic ratio of Douglas-fir needles did not differ whether trees were grown in monoculture or in mixtures with red alder. We conclude that lower soil fertility and contrasting microclimate at one site relative to the other suppressed NPP while maintaining higher transpiration, thus reducing water use efficiency.     

森林在环境和发展中的作用与地位

本文阐述了森林在环境和发展中的作用及地位, 其主要表现在3个方面: 森林是全球生态环境问题的核心; 森林是环境与经济协调持续发展的关键; 森林是人类赖以生存和创造文明的基础。文章论述了国际社会对上述3个问题的研究成果、结论和应用。     

城市树木养护与树艺学:欧美的做法及启示

城市树木是绿色基础设施的基本组成,是城市林业建设的基础,树木的管护水平决定了城市树木的生存质量。欧美城市树木养护和管理方面已形成专门的职业技术体系,并产生了树艺学(Arboriculture)学科。文中通过文献分析和研究,对欧美城市树木管理的教育、职业资格认证、职业要求情况进行总结分析,指出我国在城市树木管护方面应拓宽职业技术渠道,促进学科专业化发展;同时,要加强鼓励市民参与树木管理监督,扩大树木工作者权利范围,增加树木风险评估内容,规范职业资格认证与加强培训。